Freeze during x264 transcoding

Description

Hello,

Recently ffmpeg freeze everytime I try to transcode an MP4 recorded by wirecast. I don't know if it's come from a wirecast update or a ffmpeg modification.
The MP4 play well with VLC/MPlayer but freeze when I try to transcode it.
To be sure I update to the lastest version of x264 and ffmpeg, it's work well with other videos, but specificaly with this one, it's still freezing.

My transcoding command was complex at the beginning but I get exactly the same phenomenom with something simple like :ffmpeg -i input.mp4 -sameq -an output.mp4

And everything seems normal in the result :
{{{ffmpeg version N-31775-g640a905, Copyright (c) 2000-2011 the FFmpeg developers
Built on Aug 8 2011 12:21:40 with gcc 4.3.2

Does it only freeze if the input is H264, or also for other video codecs?
Does latest FFmpeg git fail with an earlier version of x264?
Does latest x264 fail with an earlier version of FFmpeg?
When did it break?

Does it only freeze if the input is H264, or also for other video codecs?

Yes this is the only format I find which freeze ffmpeg like this. I also tried with other wirecast export like vp6 or mov, but they didn't fail at transcoding.

When did it break?

I find when the problem appear. In previous version of wirecast 3.X, baseline was the default h264 profil, but since few time with the new version 4.X, Main profile is the default value. If I try the same process than before and just change the profile to Baseline, there is absolutely no problem and the MP4 transcode well.

Does latest FFmpeg git fail with an earlier version of x264?

Yes, I try with a x264 snapshot of december and I get the same problem.

Does latest x264 fail with an earlier version of FFmpeg?

Yes, I try with an ffmpeg 0.6.1 and I get the same problem.

I'm looking to get a backtrace later because I don't have the debug binary on this server.